1. Field of the Invention
The present application relates to power converters, such as those utilized in modern data communications and data processing systems.
2. Background of the Invention
Most modern data processing and/or communication systems are created and designed using digital logic techniques. Digital logic is based on mathematical manipulation of two different symbols, such as logical zero (xe2x80x9c0xe2x80x9d) and logical one (xe2x80x9c1xe2x80x9d). When digital logic design techniques are utilized, system designers employ a number of combinational or other type symbolic digital logic elements (e.g., drawings and associated logic tables of AND gates, OR gates, and/or microprocessors or other computational devices which operate on digital logic) in order to create xe2x80x9cpaperxe2x80x9d or xe2x80x9csymbolicxe2x80x9d designs of data processing and/or data communication systems.
At some point, the digital logic system designers often attempt to implement their symbolic digital logic designs. One common way in which this is done is to implement the symbolic system via an electrical system which mimics the symbolic digital logic design, wherein digital logic zero (xe2x80x9c0xe2x80x9d) is mimicked via a DC voltage signal having a relatively low voltage value (e.g., logical zero is mimicked via a DC voltage signal set at 0.2 volts) and digital logic one (xe2x80x9c1xe2x80x9d) is mimicked via a DC voltage signal having a relatively high voltage value (e.g., logical zero is mimicked via a DC voltage signal set at 1 volt). Electrical systems which are used to mimic symbolic digital logic design are hereinafter referred to as xe2x80x9cdigital logic electrical systems.xe2x80x9d
As noted, digital logic electrical systems typically use DC power at relatively low voltage levels. However, those having ordinary skill in the art will recognize that readily available power is generally AC power of relatively high voltage (e.g., the 120 Volt, 60 Hertz AC power available from the North American power grid). Accordingly, in order for such power to be used with digital logic electrical systems, it is necessary to convert such relatively high-voltage AC power to the desired relatively low-voltage DC power. This is typically accomplished in the related art via what will be referred to herein as xe2x80x9cpower converters.xe2x80x9d (Although power converters are being introduced herein in the context of digital logic electrical systems for sake of illustration, those having ordinary skill in the art will appreciate that, as used herein, the term xe2x80x9cpower converterxe2x80x9d is intended to refer to devices which convert electrical power from one form to another (e.g., devices which convert between AC and DC power (or vice versa), devices which convert between high-voltage DC power and low-voltage DC power (or vice versa), devices which convert between high-voltage AC power and low-voltage AC power (or vice versa), etc.))
When power converters are used to power digital logic electrical systems, it is critically important that the electrical signals produced by the power converters be held relatively constant. For example, in a digital logic electrical system where 0.2 volts is utilized to represent logical zero, and 1 volt is utilized to represent logical one, it can be seen that only a 0.8 volt potential difference exists between the electrical signals representative of logical zero and logical one. Accordingly, it is very important that the electrical signals representative of logical zero and logical one fluctuate as little as possible from their desired values.
Unfortunately, fluctuations in electrical signalsxe2x80x94even DC electrical signalsxe2x80x94are built into the very nature of electrical signals themselves, so in practice it has turned out to be surprisingly difficult to create stable electrical signals representative of logical zeroes and ones. It has been noted by system designers that one significant source of such fluctuations are DC power sources which are used to power digital logic electrical systems. That is, digital logic electrical systems are generally powered by some DC power source, and it has been long recognized that if the output voltage of a DC power source which powers a digital logic electrical system varies, or ripples, such variance or ripple tends to drag the electrical signals throughout the digital logic electrical system up and down, thereby introducing potential sources of digital logic errors into the system.
One way that the foregoing-noted source of error is often dealt with is to use power converters which begin with an extremely high-voltage DC power source wherein the variation, or ripple, in the DC output is tightly controlled (or regulated). Thereafter, the high voltage of the DC power source is successively divided downward, and such divided-down voltage is ultimately utilized to power a digital logic electrical system. Insofar as the DC voltage driving the electrical system is a divided-down version of the high-voltage DC power source, likewise the fluctuations in the DC voltage driving the electrical system are divided-down versions of the fluctuation of the voltage of the DC power source. Hence, provided that the fluctuation of the high-voltage DC power source has been held relatively constant, the DC power source driving the digital logic electrical system is generally extremely stable, which thereby allows the digital logic electrical system to operate in a substantially error free manner. One such type of power converter is known as a xe2x80x9cswitched mode power supply.xe2x80x9d
With reference to the figures, and with reference now to FIG. 1A, shown is a related-art switched mode power supply. Illustrated is that rectifier-filter section 102 receives as input a 120 volt AC power signal (e.g., from a wall socket), and transmits as output a rectified and smoothed version of the 120 volt AC power signal (e.g., a quasi-DC (or xe2x80x9cripplyxe2x80x9d) version of the 120 volt signal, where the amount of ripple present depends upon the amount of the filtering used). Shown is that electrical xe2x80x9cgatingxe2x80x9d or xe2x80x9cchoppingxe2x80x9d device 104 receives as input the quasi-DC output of rectifier-filter section 102. Depicted is that chopping device 104 intermittently interrupts the received quasi-DC power signal in order to create a high-frequency time-varying (i.e., alternating current, or xe2x80x9cACxe2x80x9d) waveform version of the DC power signal as seen by the input of transformer 106 (e.g., chopping device 104 connecting the quasi-DC voltage to the input of transformer 106 for {fraction (1/16000)} of a second, then disconnecting the quasi-DC voltage from the input of transformer 106 for {fraction (1/16000)} second, then reconnecting the quasi-DC voltage to the input of transformer 106 for {fraction (1/16000)} of a second, etc., such that the input of transformer 106 experiences the output of chopping device 104 as essentially an 8000 Hertz (cycles per second) square wave having amplitude varying between 0 and the DC voltage that results from an AC-rectified signal). Illustrated is that transformer 106 accepts as input the created time-varying, or alternating current (AC), power signal and transmits as output a xe2x80x9cstepped down,xe2x80x9d voltage version of its higher-frequency AC power input signal (transformer 106 is shown and described as what is known in the art as a xe2x80x9cstep-downxe2x80x9d transformer). Thereafter, illustrated is that rectifier-filter-regulator device 108 converts the higher-frequency AC power electrical output of the step-down transformer into circuit-voltage stable DC power (e.g., DC power at a stable 1 volt potential), such stable DC power being thereafter available to power digital logic electrical systems.
With reference now to FIG. 1B, shown is the related-art power converter of FIG. 1A, but with the addition of feedback circuitry. Depicted is that output-voltage monitor 112 receives a monitored voltage signal 114. In the related art, output-voltage monitor 112 generally transmits a xe2x80x9cfeedbackxe2x80x9d control signal 116 to rectifier-filter device 102, where control signal 116 is such that it controls the voltage level of the output of rectifier-filter device 102 such that the time-averaged DC voltage output of rectifier-filter-regulator device 108 is within predefined limits.
At this point, it is helpful to discuss at least one reason why the related art uses the foregoing described multi-stage scheme to achieve power conversion. One reason why the related art uses the foregoing scheme is that, from a practical standpoint, there is a relationship which indicates that the higher the frequency of a waveform applied to a transformer, the cheaper and more efficient a transformer can be made, because the magnetic components within a transformer will generally weigh less, require less material, or have less power loss at higher frequencies. Accordingly, by increasing the frequency of the waveform to be applied to a transformer, a system can use smaller, cheaper, and cooler-running transformers and/or inductors, which gives multiple increases across various efficiencies (e.g., electrical transfer efficiency, cooling efficiency, component life, etc.).
In one embodiment, a method for use in a power converter includes: monitoring a magnitude of an input of a power-flow controller; generating a pulse-width modulated signal wherein at least one pulse has width correlated with a difference between a reference and the monitored magnitude; and varying an output power flow of the power-flow controller in response to the pulse-width modulated signal.
In another embodiment of the method, the power converter is characterized by a power converter selected from the group including but not limited to a power supply, a power controller, and a power regulator.
In another embodiment of the method, generating a pulse-width modulated signal wherein at least one pulse has width correlated with a difference between a reference and the monitored magnitude is characterized by: adjusting a pulse width in response to a time during which a reference saw-tooth waveform magnitude substantially exceeds the monitored magnitude.
In another embodiment of the method, adjusting a pulse width in response to a time during which a reference saw-tooth waveform magnitude substantially exceeds the monitored magnitude is characterized by: triggering a leading edge of a pulse in response to the reference saw-tooth waveform magnitude substantially exceeding the monitored magnitude and triggering a trailing edge of the pulse in response to the reference saw-tooth waveform magnitude equaling or falling below the monitored magnitude.
In another embodiment of the method, adjusting a pulse width in response to a time during which a reference saw-tooth waveform magnitude substantially exceeds the monitored magnitude is characterized by: summing a saw-tooth waveform with a DC offset to achieve the reference saw-tooth waveform magnitude.
In another embodiment of the method, summing a saw-tooth waveform with a DC offset to achieve the reference saw-tooth waveform magnitude is characterized by: adjusting the DC offset in response to an average output voltage level of the power-flow controller.
In another embodiment of the method, the summing a saw-tooth waveform with a DC offset to achieve the reference saw-tooth waveform magnitude is characterized by: adjusting the saw-tooth waveform amplitude in response to at least one variation in an output voltage magnitude of the power-flow controller.
In another embodiment of the method, varying an output power flow of the power-flow controller in response to the pulse-width modulated signal is characterized by: gating a power flow control device selected from the group including but not limited to a power transistor, a field effect transistor (e.g., a FET or MOSFET), and an insulated-gate, bipolar transistor (IGBT) where the gating is such that energy transfer is more restricted when the input voltage magnitude is larger relative to a threshold and is less restricted when the input voltage magnitude is smaller relative to the threshold.
In another embodiment of the method, gating a power flow control device is characterized by: gating the power flow control device interposed between an input of the power flow controller and an input of a transformer internal to the power-flow controller.
In another embodiment of the method, gating the power flow control device interposed between an input of the power flow controller and an input of a transformer internal to the power-flow controller is characterized by: gating the power flow control device interposed between an input of the power flow controller and an input of a step-down transformer internal to the power-flow controller.
In another embodiment of the method, gating the power flow control device interposed between an input of the power flow controller and an input of a transformer internal to the power-flow controller is characterized by: gating the power flow control device interposed between an input of the power flow controller and an input of a step-up transformer internal to the power-flow controller.
In another embodiment of the method, generating a pulse-width modulated signal wherein at least one pulse has width correlated with a difference between a reference and the monitored magnitude is characterized by: adjusting a pulse width in response to a digital signal processor calculation based on a digitized value representing the monitored magnitude.
In another embodiment of the method, generating a pulse-width modulated signal wherein at least one pulse has width correlated with a difference between a reference and the monitored magnitude is characterized by: adjusting a pulse width in response to a digital signal processor calculation based on both a digitized value representing the monitored magnitude and a digitized value representing a magnitude of an output of the power controller in order to regulate an average output voltage magnitude.
In another embodiment of the method, generating a pulse-width modulated signal wherein at least one pulse has width correlated with a difference between a reference and the monitored magnitude is characterized by: adjusting a pulse width in response to a digital signal processor calculation based on both a digitized value representing the monitored magnitude and a digitized value representing a magnitude of an output of the power controller in order to control the quality of output regulation (e.g., to reduce short-term variations in the magnitude of the output voltage).
In one or more various embodiments, related systems include but are not limited to circuitry and/or programming for effecting the foregoing-referenced method embodiments; the circuitry and/or programming can be virtually any combination of hardware, software, and/or firmware configured to effect the foregoing-referenced method embodiments depending upon the design choices of the system designer.
In one embodiment, a power converter includes but is not limited to a forward-looking control device.
In another embodiment of the power converter, the power converter is characterized by the power converter selected from a power-converter group including but not limited to a power supply, a power controller, and a power regulator.
In another embodiment of the power converter, the power converter is characterized by the forward-looking control device operably coupled to a quasi-DC power input of a power controller.
In another embodiment of the power converter the power converter is characterized by the forward-looking control device operably coupled to an output of the power converter.
In another embodiment of the power converter, the forward-looking control device is characterized by a pulse-width control circuit.
In another embodiment of the power converter, the pulse-width control circuit is characterized by a comparator circuit; and a reference voltage circuit.
In another embodiment of the power converter, the forward-looking control device is characterized by an average power-converter-output-voltage control circuit.
In another embodiment of the power converter, the average power-converter-output-voltage control circuit is characterized by a reference amplifier and filter circuit; an offset adjust circuit; and a reference voltage circuit.
In another embodiment of the power converter, the forward-looking control device is characterized by a power-converter-output-voltage ripple control circuit.
In another embodiment of the power converter, the power-converter-output-voltage ripple control circuit is characterized by a ripple detector circuit; a voltage controlled amplifier circuit; and a reference voltage circuit.
The foregoing is a summary and thus contains, by necessity; simplifications, generalizations and omissions of detail; consequently, those skilled in the art will appreciate that the summary is illustrative only and is NOT intended to be in any way limiting. Other aspects, inventive features, and advantages of the devices and/or processes described herein, as defined solely by the claims, will become apparent in the non-limiting detailed description set forth herein.